This invention relates to apparatus and methods for inserting corner members in channel-shaped flanges of a duct.
A typical sheet metal duct section of the type used in heating, ventilating, and air-conditioning systems (HVAC systems) is usually square or rectangular in cross-sectional shape. Such a duct section usually has channel-shaped flanges extending outwardly from its end edges for end-to-end attachment to another duct section. Corner members (or angle plates) having first and second legs are inserted into adjacent flanges of the duct in a manner so that the first leg is in one flange and the second leg is in the other flange. The flanges are then crimped to secure the corner members in the flanges. Each corner member has at least one aperture therethrough. When duct sections are positioned end-to-end, then the corner member apertures of one duct section align with the corner member apertures of the other duct section. The aligned apertures are sized and configured for receiving threaded fasteners (e.g., bolts and nuts) to clamp the duct sections together.
Insertion of the corner members into the flanges is typically performed manually. A technician places a corner member on the flanges, forces the corner members into the channel-shaped flanges with a hammer or other suitable tool such as pliers, and then manually crimps the flanges. The primary problems associated with such manual insertion are that this operation is labor intensive and time consuming.
Machines have been used to automatically remove a corner member from a stack of corner members and insert it into duct flanges. With such machines, the duct is first clamped in a fixed position on the machine. A corner member is then removed from the stack, brought into engagement with the duct, and pressed into the duct flanges. After the corner member is pressed into the duct flanges, the machine crimps the flanges to retain the corner member in the flanges. A problem associated with such machines is that a user cannot determine whether a corner member is mis-fed from the stack (or not fed from the stack at all) until after the duct-crimping step is completed. This may result in damage to the duct and delays in the insertion process.